Enabling Practical IPsec authentication for the Internet

On the Move to Meaningful Internet Systems 2006: OTM 2006 Workshops (First International Workshop on Information Security (IS'06), OTM Federated Conferences and workshops). Montpellier, Oct,/Nov. 2006There is a strong consensus about the need for IPsec, although its use is not widespread for end-to-end communications. One of the main reasons for this is the difficulty for authenticating two end-hosts that do not share a secret or do not rely on a common Certification Authority. In this paper we propose a modification to IKE to use reverse DNS and DNSSEC (named DNSSEC-to-IKE) to provide end-to-end authentication to Internet hosts that do not share any secret, without requiring the deployment of a new infrastructure. We perform a comparative analysis in terms of requirements, provided security and performance with state-of-the-art IKE authentication methods and with a recent proposal for IPv6 based on CGA. We conclude that DNSSEC-to-IKE enables the use of IPsec in a broad range of scenarios in which it was not applicable, at the price of offering slightly less security and incurring in higher performance costs.Universidad de Montpellier IIPublicad

Multivariate analysis of bar fractions in the local Universe

Treballs Finals de Grau de Física, Facultat de Física, Universitat de Barcelona, Curs: 2023, Tutor: Josep Maria SolanesThis study presents a detailed investigation of bar abundances in present-day disk galaxies partitioned into morphological and activity classes. The relationship between bar fractions, and both the stellar mass and local environmental density of the galaxies has been examined using data from the literature that rely on two different bar identification procedures applied to objects extracted from two Sloan surveys, one based on SDSS and the other on MaNGA observations. Our study reveals that galaxies of all Hubble and BPT types show a more or less pronounced tendency to exhibit higher bar fractions with increasing stellar mass, being, respectively, the Sc and Seyfert galaxy classes the ones in which these transient structures are more abundant. We also detect two distinct regimes in the behaviour of the bar fraction with this parameter that, we speculate, could be related to the golden mass of galaxy formation. In contrast, the bar fraction is found to exhibit a weak or negligible dependence on the local baryon density. Although the results inferred from the two catalogues analysed show an overall consistency, there are some discrepancies in the behaviour of the predicted bar fractions, more obvious in the high-mass regime, that can hardly be explained unless there are hidden biases in the selection functions of the dataset

El campo semántico de la educación en el NT: παιδεύω y διδασκαλία según el DGENT

El presente trabajo comenzará atendiendo a la diversidad de lemas que ambos términos han merecido en los diccionarios dedicados a la lengua griega, prestando especial atención a aquéllos centrados en el griego neotestamentario. A continuación, partiendo de esos juicios previos, se analizarán, siguiendo las directrices utilizadas por el DGENT, y se argumentarán las novedades que dicho análisis presenta respecto de los diccionarios tradicionales. En este sentido, nuestro objetivo será, en primer lugar, tratar de descubrir cuál es el significado lexical de ambos términos, dando una definición de cada uno de ellos, así como de sus respectivas acepciones. Seguidamente, nos centraremos en identificar las causas o factores conceptuales que determinan que παιδεύω y διδασκαλία tengan distinto significado y traducción cuando aparecen en uno u otro contexto. Finalmente, aportaremos los versículos en los que aparece el significado propuesto

Enhancement of Student Learning Through the Use of a Hinting Computer e-Learning System and Comparison with Human Teachers

This paper reports the results of an experiment in a Computer Architecture Laboratory course classroom session, in which students were divided into two groups for interaction both with a hinting e-learning system and with human teachers generating hints. The results show that there were high learning gains for both groups, demonstrating the effectiveness of the human teachers as well as of the computer-based hinting e-learning system even without the use of adaptive and personalization capabilities. In addition, in the worst case, the difference in favor of human teachers (with a low student-to-teacher ratio of 13.5 students per teacher) would not be significant with respect to the e-learning system, so the computer-based system can replace teachers without a significant loss of effectiveness.This work was supported in part by the Learn3 project TIN2008-05163/TSI within the Spanish “Plan Nacional de I+D+I,” and by the Madrid regional community project eMadrid S2009/TIC-1650.Publicad

Using bluetooth to implement a pervasive indoor positioning system with minimal requirements at the application level

Proyecto CCG10-UC3M/TIC-4992 de la Comunidad Autónoma de Madrid y la Universidad Carlos III de MadridPublicad

Deciding on different hinting techniques in assessments for intelligent tutoring systems

Intelligent Tutoring Systems (ITSs) must take advantage of their high computing capabilities and capacity for information retrieval in order to provide the most effective methodologies for improving students' learning. One type of ITS provides assessments to students and some help as a hint, when they do not know how to solve a problem. Our thesis is that the type of hinting techniques used without changing the contents can influence the learning gains and aptitudes of students. We have implemented some hinting techniques as an extension to the XTutor ITS. We found that some hinting techniques can produce a signi cant increase in students' knowledge with respect to others, but the improvement and direction of the comparison depended on some other factors such as the topics to which it was applied. We conclude that proper adaptation of hinting techniques based on different information of the systems will imply better student learning gains. In addition, the results of a student survey, which includes the students' ratings of the different hinting features they interacted with, leads to high variances, which reinforce the idea of the importance of adaptation of hinting techniques in these types of systems.This work was supported in part by the MEC-CICYT Learn3 project TIN2008-05163/TSI (Spanish Ministry of Science and Education, Programa Nacional de Tecnologías de la Información y de las Comunicaciones), and the e-Madrid project S2009/TIC-1650 (Madrid Regional Community).Publicad

Bounded and unbounded polynomials and multilinear forms: Characterizing continuity

In this paper we prove a characterization of continuity for polynomials on a normed space. Namely, we prove that a polynomial is continuous if and only if it maps compact sets into compact sets. We also provide a partial answer to the question as to whether a polynomial is continuous if and only if it transforms connected sets into connected sets. These results motivate the natural question as to how many non-continuous polynomials there are on an infinite dimensional normed space. A problem on the \emph{lineability} of the sets of non-continuous polynomials and multilinear mappings on infinite dimensional normed spaces is answered.Comment: 8 page

Personalized Service-Oriented E-Learning Environments

6 pages, 4 figures.The social component of Web 2.0-related services is providing a new open and personal approach to how we expect things to solve problems in our information-driven world. In particular, students' learning needs require open, personal e-learning systems adapted to life-long learning needs in a rapidly changing environment. It therefore shouldn't be surprising that a new wave of ideas centered on pervasive systems has drawn so much attention. This article analyzes current trends in the evolution of e-learning architectures and describes a new architecture that captures the needs of both formal (instructor-led) and informal (student-led) learning environments.Spain’s Programa Nacional de Tecnologías de la Sociedad de la Información supported this research through projects TSI2005-08225-C07-01 and -02.Publicad

Sending learning pills to mobile devices in class to enhance student performance and motivation in network services configuration courses

Teaching electrical and computer software engineers how to configure network services normally requires the detailed presentation of many configuration commands and their numerous parameters. Students tend to find it difficult to maintain acceptable levels of motivation. In many cases, this results in their not attending classes and not dedicating enough time to acquire the required competencies. This paper describes a successful experiment that was able to improve student class attendance, performance, and motivational patterns by using mobile devices in class to provide students with contextualized learning pills. A learning pill is a simple exercise that summarizes some of the key concepts explained in class and promotes reflection and self-study. Each student attending a particular lecture or laboratory session automatically receives a learning pill on his or her mobile phone just after the related concept has been presented. This paper details the scenario used in the experiment and analyzes the performance and motivational patterns of 170 students at the Higher Polytechnic School, Carlos III University of Madrid, Leganes, SpainThis work was supported by the ARTEMISA project TIN2009- 14378-C02-02 within the Spanish “Plan Nacional de I+D+I” and the Madrid regional community projects S2009/TIC-1650 and CCG10-UC3M/TIC-4992.Publicad